Dynamic Shadow Elimination for Multi-Projector Displays

Rahul Sukthankar, Tat-Jen Cham, and Gita Sukthankar
Proceedings of IEEE Computer Conference on Computer Vision and Pattern Recognition, 2001, pp. 151 - 157.


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Abstract
A major problem with interactive displays based on front-projection is that users cast undesirable shadows on the display surface. This situation is only partially-addressed by mounting a single projector at an extreme angle and pre-warping the projected image to undo keystoning distortions. This paper demonstrates that shadows can be muted by redundantly-illuminating the display surface using multiple projectors, all mounted at different locations. However, this technique does not eliminate shadows: multiple projectors create multiple dark regions on the surface (penumbral occlusions). We solve the problem by using cameras to automatically identify occlusions as they occur and dynamically adjust each projector's output so that additional light is projected onto each partially-occluded patch. The system is self-calibrating: relevant homographies relating projectors, cameras and the display surface are recovered by observing the distortions induced in projected calibration patterns. The resulting redundantly-projected display retains the high image quality of a single-projector system while dynamically correcting for all penumbral occlusions. Our initial two-projector implementation operates at 3 Hz.

Keywords
projector camera systems, computer vision

Notes
Number of pages: 7

Text Reference
Rahul Sukthankar, Tat-Jen Cham, and Gita Sukthankar, "Dynamic Shadow Elimination for Multi-Projector Displays," Proceedings of IEEE Computer Conference on Computer Vision and Pattern Recognition, 2001, pp. 151 - 157.

BibTeX Reference
@inproceedings{Sukthankar_2001_4380,
   author = "Rahul Sukthankar and Tat-Jen Cham and Gita Sukthankar",
   title = "Dynamic Shadow Elimination for Multi-Projector Displays",
   booktitle = "Proceedings of IEEE Computer Conference on Computer Vision and Pattern Recognition",
   pages = "151 - 157",
   year = "2001",
   volume = "2",
}